chore: update coverage tools (#647)

This change takes advantage of the latest coverage tools released in
[v1.39](https://deno.com/blog/v1.39).

Author: iuioiua

.gitignore

@@ -5,4 +5,5 @@ cov.lcov
 .idea
 _fresh/
 backup.json
-html_cov/
+html_cov/
+coverage/

deno.json

@@ -8,13 +8,11 @@
     "db:migrate": "deno run --allow-read --allow-env --allow-net --unstable tasks/db_migrate.ts",
     "db:reset": "deno run --allow-read --allow-env --unstable tasks/db_reset.ts",
     "start": "deno run --unstable -A --watch=static/,routes/ --env dev.ts",
-    "test": "DENO_KV_PATH=:memory: GITHUB_CLIENT_ID=xxx GITHUB_CLIENT_SECRET=xxx deno test -A --unstable --parallel --coverage=./cov",
+    "test": "DENO_KV_PATH=:memory: GITHUB_CLIENT_ID=xxx GITHUB_CLIENT_SECRET=xxx deno test -A --unstable --parallel --coverage",
     "check:license": "deno run --allow-read --allow-write tasks/check_license.ts",
     "check:types": "deno check **/*.ts && deno check **/*.tsx",
     "ok": "deno fmt --check && deno lint && deno task check:license --check && deno task check:types && deno task test",
-    "cov:clean": "rm -rf cov html_cov cov.lcov",
-    "cov:gen": "deno coverage ./cov/ --lcov --exclude='.tsx' --output=cov.lcov",
-    "cov:view": "genhtml -o html_cov cov.lcov && open html_cov/index.html",
+    "cov:gen": "deno coverage coverage --lcov --exclude='.tsx' --output=cov.lcov",
     "update": "deno run -A -r https://fresh.deno.dev/update .",
     "build": "deno run -A --unstable dev.ts build",
     "preview": "deno run -A --unstable main.ts"